WordPress Plugin Not Working? How to Diagnose and Fix It

WordPress plugin issues are one of the most common — and most frustrating — problems site owners run into. The plugin worked yesterday. Nothing changed. Now it doesn’t. Here’s how to systematically diagnose and fix a WordPress plugin that’s not working, without breaking anything else in the process.

Start Here: What “Not Working” Actually Means

Before diving into fixes, narrow down what you’re actually seeing. Plugin failures in WordPress usually fall into one of these categories:

• Plugin is active but has no effect — the feature it’s supposed to provide simply isn’t showing up
• Plugin causes a white screen or fatal error — the site breaks when the plugin is active
• Plugin settings aren’t saving — configuration changes don’t stick
• Plugin conflicts with another plugin or theme — works in isolation but breaks in context
• Plugin worked after update but stopped after another update — a WordPress core, theme, or other plugin update broke compatibility

Knowing which category you’re in saves significant time. A plugin that has no effect is a different problem from a plugin causing a fatal error.

Step 1: Check the Basics First

Before assuming something is broken, verify the obvious:

• Is the plugin actually activated? Go to Plugins → Installed Plugins and confirm it shows “Deactivate” (meaning it’s active). A plugin that’s installed but not activated does nothing.
• Are you looking in the right place? Some plugins add functionality to specific post types, user roles, or pages only. Check whether the plugin is doing something — just not where you expect.
• Is the plugin license valid? Premium plugins often silently stop functioning when a license expires. Check the plugin’s settings page for license status.
• Has the plugin been updated recently? Check the plugin’s changelog. A recent update may have changed how a feature works or where a setting lives.

Step 2: Deactivate All Other Plugins (Conflict Test)

Plugin conflicts are the most common cause of plugins not working correctly. The fastest way to test for a conflict is to deactivate everything except the plugin you’re troubleshooting.

1. Go to Plugins → Installed Plugins
2. Select all plugins except the one you’re testing
3. Use the bulk action dropdown to Deactivate
4. Test the plugin in isolation

If the plugin works now, you have a conflict. Reactivate your other plugins one at a time, testing after each activation, until the problem returns. The last plugin you activated before the problem returned is the conflict.

If the plugin still doesn’t work with everything else deactivated, the conflict is with your theme — or the plugin itself is the issue.

Step 3: Switch to a Default Theme

Themes can conflict with plugins just as other plugins can. Temporarily switch to a default WordPress theme (Twenty Twenty-Four or Twenty Twenty-Three) and test the plugin again.

If the plugin works with the default theme, your active theme is the conflict. You’ll need to either find a workaround, contact your theme developer, or find an alternative plugin that doesn’t conflict.

Step 4: Check for PHP Errors

Many plugin failures produce PHP errors that are hidden from the front end by default. Enabling debug mode temporarily will surface these.

Add the following to your wp-config.php file (above the line that says “That’s all, stop editing”):

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );

With these settings, errors are written to /wp-content/debug.log rather than displayed on screen. Check that file after reproducing the problem — any errors logged there will point to what’s failing and which file is responsible.

Important: disable debug mode on a production site once you’ve diagnosed the issue. Remove those lines from wp-config.php or set WP_DEBUG back to false.

Step 5: Check PHP Version Compatibility

Plugin developers build and test against specific PHP versions. If your hosting environment is running an older PHP version, newer plugins may fail silently or produce errors.

To check your PHP version: go to Tools → Site Health → Info → Server and look for the PHP version listed there.

Then check the plugin’s WordPress.org page or documentation for its minimum PHP requirement. If you’re running PHP 7.4 and the plugin requires 8.0+, that’s your problem. Contact your host about updating PHP — most managed hosts make this straightforward.

Step 6: Check for JavaScript Errors

Some plugins rely heavily on JavaScript for their front-end functionality. If JavaScript is broken or conflicting, the plugin may appear to do nothing even though it’s running on the server side.

Open your browser’s developer tools (F12 in Chrome or Firefox), go to the Console tab, and reload the page with the plugin active. Red errors in the console indicate JavaScript failures. Note the error message and the file it references — this usually points to a plugin or theme conflict at the JS level.

Step 7: Clear All Caches

Caching plugins, server-side caches, CDN caches, and browser caches can all serve stale versions of pages that make a functioning plugin appear broken. Before concluding something isn’t working, clear everything:

• Clear your caching plugin’s cache (W3 Total Cache, WP Super Cache, WP Rocket, etc.)
• Clear server-side cache if your host provides one (WP Engine, Kinsta, and most managed hosts have a cache purge button in the dashboard)
• Clear your CDN cache if you’re using Cloudflare or similar
• Hard refresh your browser (Ctrl+Shift+R on Windows, Cmd+Shift+R on Mac)

If the plugin works after clearing cache, add a cache exclusion rule for the pages or post types where the plugin is active.

Step 8: Deactivate, Delete, and Reinstall the Plugin

Plugin files can become corrupted during a failed update. If none of the above has resolved the issue, do a clean reinstall:

1. Note any settings you’ve configured in the plugin — take screenshots if needed
2. Deactivate the plugin
3. Delete it entirely (Plugins → Delete)
4. Go to Plugins → Add New, search for the plugin, and reinstall it fresh
5. Reconfigure your settings

For premium plugins, download a fresh copy from the developer’s website rather than reinstalling through the WordPress dashboard.

Step 9: Check File Permissions

Incorrect file permissions on your server can prevent plugins from reading or writing files they need to function. This is more common on VPS or shared hosting environments where permissions can get misconfigured.

Standard WordPress file permissions are:

• Directories: 755
• Files: 644
• wp-config.php: 440 or 400

If you have SFTP or SSH access, you can check and fix permissions directly. If you’re on managed hosting, contact support — permission issues are usually something they can fix quickly.

Step 10: Check the Plugin’s Support Forum

If you’ve worked through the above steps and the plugin still isn’t working, search the plugin’s support forum on WordPress.org. The issue you’re experiencing has likely been reported by someone else. Look for:

• Your exact error message or symptom in recent threads
• Replies from the plugin developer acknowledging a known bug
• A workaround posted by another user

If you don’t find an existing thread, open a new support request with as much detail as possible: your WordPress version, PHP version, the plugins you have active, and the exact symptom you’re seeing.

When a Plugin Is Genuinely Broken

Sometimes a plugin is simply broken — a bad update that the developer hasn’t patched yet, a compatibility issue with a recent WordPress core release, or an abandoned plugin that no longer receives maintenance.

If you’ve confirmed the plugin itself is the problem:

• Roll back to a previous version using a plugin like WP Rollback, which lets you install earlier versions from the WordPress.org repository
• Find an alternative plugin that provides the same functionality without the compatibility issues
• Contact the plugin developer directly — many commercial plugin companies are responsive to bug reports, especially if you have an active license

Preventing Plugin Problems Going Forward

Most plugin failures are preventable with basic maintenance habits:

• Update plugins on a staging site first before pushing to production. Most managed WordPress hosts include staging environments for this reason.
• Don’t run plugins that haven’t been updated in over a year. Check the “Last Updated” date on the WordPress.org plugin page before installing anything new.
• Keep the number of active plugins reasonable. Every plugin is a potential conflict point and performance drain. Audit your plugin list periodically and deactivate anything you’re not actively using.
• Take a backup before updating anything. A reliable backup means a plugin failure is a minor inconvenience rather than a crisis.

Still Stuck?

Plugin conflicts and backend failures can get complicated quickly — especially when multiple plugins interact, custom code is involved, or the error only surfaces in specific conditions. If you’ve worked through this list and can’t isolate the problem, it’s worth getting a second set of eyes on it.

CriticalWP handles exactly this kind of issue as part of our managed WordPress maintenance plans — ongoing updates, conflict resolution, and someone accountable when things break. Learn more about WordPress maintenance →